For each category it adds up the notional whales put in and took out over the window, buys positive and sells negative, and reports the net. A category with a large positive net is one whales are accumulating.

It then does the same thing again over only the wallets scoring 60 or higher on the smart money score, which is the line between "a whale" and "a whale with a record". Comparing the two is the point: all whale flow tells you where the money is, smart money flow tells you where the money that has been right before is.

• Windows: 24 hours, 7 days or 30 days. The short window is reactive and noisy, the long one shows positioning.
• Both flows pointing the same way in a category is a consensus signal, and a weak one: everyone already sees it.
• They disagree when the crowd is buying something the ranked wallets are selling, or the reverse. That is the more interesting case, and the one worth opening a market over.
• The accompanying list of markets the top wallets are accumulating is the specific version of the same question.

GET /v1/smart-money-flow returns the same numbers, taking a range of 24h, 7d or 30d. The site widget and the API read the same cache, so they never disagree.